#!/usr/bin/env python
"""
The first two consecutive numbers to have two distinct prime factors are:

14 = 2  7
15 = 3  5

The first three consecutive numbers to have three distinct prime factors are:

644 = 2  7  23
645 = 3  5  43
646 = 2  17  19.

Find the first four consecutive integers to have four distinct primes factors. What is the first of these numbers?
"""

# 2010-06-03
f = open("primes1000000", "r")
def factors_count(num):
    n = int(num)
    f.seek(0)
    factors = []
    while n <> 1:
        lines = f.readline()
        # print lines
        line = int(lines)
        while( n % line == 0):
            factors.append(line)
            n = n / line
    # oprint factors
    return len(set(factors))
            

if __name__ == "__main__":    
#    print factors_count(644)
    n = 646
    while not (4 == factors_count(n) ==  factors_count(n+1) == factors_count(n+2) == factors_count(n+3)):
        n = n + 1
    print n
